1. Field of the Invention
The present invention relates generally to containers for living plants and more specifically to self controlled watering planter devices.
2. Description of the Prior Art
The urban and suburban nature of modern living has led to a proliferation in the use of potted plants as decorative items. Living potted plants are commonly found in private homes, restaurants, hotels, office buildings and many other locations. Consequently, devices for containing and caring for potted plants have become a major commodity.
One of the most desirable types of potted plant devices available is the self watering planter. Self watering planters are devices containing relatively large water or fluid reservoirs which may be periodically filled and which then dispense the water to the plant as the plant requires it. Self watering planters have been devised to operate by way of timer systems or by way of constant low volume seepage into the soil surrounding the plant. One of the most effective self watering planters, however, is the type wherein a sensor is placed within the soil of the plant to sense the level of moisture in the soil and cause additional water to be delivered to the soil if the moisture level is too low. Sensing self watering planters of this type have utilized electrical sensing units, an expensive and possibly dangerous solution, and porous hydrophilic (water loving) sensors.
Porous hyrophilic sensing devices allow air to pass through the porous material when it is dry but prohibit the passage of air when the porous material is wet. The porous sensor is connected to an air-tight water reservoir such that when the sensor is blocked by water, atmospheric pressure cannot reach the water reservoir and vacuum pressure prevents the delivery of water to the soil of the plant.
A self watering planter using a porous hydrophilic sensor is described in U.S. Pat. No. 3,758,987 issued to W. Crane, Jr. The Crane patent discloses a self watering planter having the inlet port to the soil located at the center of the bottom interior of the planter. In a device of this construction, the water enters the soil from the bottom while the sensor measures the moisture content of the soil near the top. When the moisture level at the sensor element is sufficiently high to block the pores such that air may no longer flow through the sensor element, the water flow into the soil is stopped.
One of the major difficulties which may be encountered in a self watering planter of the porous sensor variety is that the roots of the plant are hydrotropic, that is they tend to grow towards the source of water. Frequently the plant roots will grow down through the soil to the inlet port of the planter and foul or clog the port such that it does not operate properly.
Another disadvantage of prior art self watering planters is that the tube connecting the sensor element to the water reservoir frequently extends above the level of the planter and is in plain view. This not only mars the beauty of the plant but in public areas, such as restaurants and hotel lobbies, frequently leads to the sensor being displaced or broken by passers-by or curious individuals.